Saturday, 16 May 2020

Removing the novel coronavirus from the water cycle

Scientists
know that coronaviruses, including the SARS-CoV-19 virus responsible for the
COVID-19 pandemic, can remain infectious for days -- or even longer -- in
sewage and drinking water.

Researchers
have called for more testing to determine whether water treatment methods are
effective in killing SARS-CoV-19 and coronaviruses in general. The virus can be
transported in microscopic water droplets, or aerosols, which enter the air
through evaporation or spray.

During
a 2003 SARS outbreak in Hong Kong, a sewage leak caused a cluster of cases
through aerosolization. Though no known cases of COVID-19 have been caused by
sewage leaks, the novel coronavirus is closely related to the one that causes
SARS, and infection via this route could be possible.

The novel coronavirus
could also colonize biofilms that line drinking water systems, making
showerheads a possible source of aerosolized transmission. This transmission
pathway is thought to be a major source of exposure to the bacteria that causes
Legionnaire's disease, for example.

Fortunately,
most water treatment routines are thought to kill or remove coronaviruses
effectively in both drinking and wastewater. Oxidation with hypochlorous acid
or peracetic acid, and inactivation by ultraviolet irradiation, as well as
chlorine, are thought to kill coronaviruses. In wastewater treatment plants
that use membrane bioreactors, the synergistic effects of beneficial
microorganisms and the physical separation of suspended solids filter out
viruses concentrated in the sewage sludge.

The
researchers suggest upgrading existing water and wastewater treatment
infrastructure in outbreak hot spots, which possibly receive coronavirus from
places such as hospitals, community clinics, and nursing homes. For example,
energy-efficient, light-emitting, diode-based, ultraviolet point-of-use systems
could disinfect water before it enters the public treatment system.

Potable
water-reuse systems, which purify wastewater back into tap water, also need
thorough investigation for coronavirus removal, and possibly new regulatory standards
for disinfection.

See:

Vincenzo
Naddeo, Haizhou Liu. Editorial Perspectives: 2019 novel coronavirus
(SARS-CoV-2): what is its fate in urban water cycle and how can the water
research community respond? Environmental Science: Water Research &
Technology, 2020; DOI: 10.1039/d0ew90015j